I'm throwing code P0683. Clearing it doesn't work - it comes right back. I know this often times means the GPCM is bad, but could just be a bad plug too. I checked the resistance at the glow plug connectors on each valve cover, but don't know what the readings really told me. On the passenger side, all four averaged around 1.5ohms. On the drivers side three of them averaged around 3.8 ohms, but the one at the back (nearest the cab) measured 5.2ohms.
What does this tell me? Is that one GP bad or is it the module? Do I need to do some further testing?
What does this tell me? Is that one GP bad or is it the module? Do I need to do some further testing?